The electrochemical oxidation of acetic acid on boron-doped diamond (BDD) electrode revealed that acetic acid adsorbs on a BDD surface resulting in an autoinhibition of its oxidation (oxidation is shifted to higher potentials). Both the adsorption and autoinhibition are fully reversible with respect to the concentration, indicating the existence of physical interactions between acetic acid and the electrode surface. Acetic acid appeared to be an inhibitor not only for its own oxidation but also for that of other compounds (Ce3+ and HCOOH) that undergo oxidation at high anodic potentials (i.e., in the vicinity of oxygen evolution). This inhibition effect is explained by the adsorption of acetic acid on the BDD surface, leading to the displacement of water from the surface and consequent decrease of water discharge rate. (C) 2008 The Electrochemical Society.